1. Field of the Invention
The present invention generally relates to a battery connection plate and more particularly to a battery connection plate and a manufacturing method therefor wherein a busbar for connecting batteries in series and a terminal for voltage detection are insert-molded in a plate body made of synthetic resin.
2. Description of the Related Art
FIG. 11 shows a conventional battery connection plate.
Battery connection plates 70,71 are provided at both ends of a battery set 72 and connect batteries 73 in series, which battery connection plates 70,71 have a plurality of conductive metal busbars 75 in parallel on an oblong plate body 74 made of synthetic resin.
The busbar 75 has a pair of through holes 78 for connecting electrodes 76,77, each having a male thread, of the neighboring two batteries 73 and is fixed to the plate body 74 by means of pressing-insertion, insert-molding, or the like. Each of electrodes 76,77 is tightly-connected with a nut 79 to the busbar 75.
A busbar 83 having one through hole 82 is fixed to both ends of the battery connection plate 70, and both the electrodes 76,77 of the battery 73 arranged at the both ends of the battery set 72 are connected through each of busbars 83 to respective power feeders (not illustrated) each having a terminal.
A cover 80 is pivotably provided on the plate body 74, and the busbars 75,83, electrodes 76,77 and nuts 79 are protected inside an accommodating portion 81 by closing the cover 80.
FIG. 12 is an exploded perspective view showing another example of a conventional battery connection plate. In this battery connection plate 85, a terminal 86 for voltage detection is provided on each of two neighboring batteries (not illustrated). The terminal 86 is insert-molded in a plate body 88 made of synthetic resin along with the busbar 87. The busbar 87 is surface-connected to a tabular electrically contacting portion 89 provided at the end of the terminal 86, electronic parts (not illustrated) such as a circuit protection element, e.g. fuse, is soldered to a middle portion 101 of the terminal 86, and a signal line 90 is pressure-welded to a base portion of the terminal 86.
Reference numeral 87 designates a busbar with two holes, 91 designates a busbar with one hole, and 92 designates a power feeder with a terminal. The terminal 86 for voltage detection is arranged inside a front circular hole 93 of the plate body 88 along with the busbar 87. The above electronic parts (not illustrated) at the middle portion 101 of the terminal 86 is arranged inside an intermediate framed portion 94. The signal line 90 bends in a right angle from a framed portion 95 and is laid inside a short groove portion 96. The power feeder 92 is laid inside another short groove portion 97. 98 designates a pivotable cover which is locked to the plate body 88 by locking means 99,100.
The insert-molding of the terminal 89 for voltage detection and the busbar 87 is carried out with a metal mold 102 as shown in FIG. 13. For example, melted resin is injected around the busbar 87 and the terminal 89 in a state that each of through holes 104 of the busbar, 87 and the terminal 89 engages a boss 103 located in a metal mold 102.
As shown in FIG. 14, a small hole 106 is provided on the electrically contacting portion 89 side and on the wire connecting portion 105 side of the terminal 86 for voltage detection. As show in FIG. 15, resin 113 enters the small holes 106 at the insert-molding, and the terminal 86 is secured. In FIG. 14, a pair of small holes 108 for connecting an electronic parts 107 is provided on the middle portion 101 of the terminal 86, lead terminals 109 of the electronic parts 107 are inserted into the small holes 108 and soldered. In case that the electronic parts 107 is of a circuit protection element, the middle portion 101 of the terminal 86 is cut off between the lead terminals 109. As is shown in FIG. 16, a male-threaded electrode 110 of the battery (not illustrated) is inserted into the through holes 104 of the busbar 87 and the terminal 86 and tightly-connected to the busbar 87 with a nut 111 by means of a tool 112 in an arrow Z1 direction.
With respect to the above a conventional structure, however, as shown in FIG. 16, when the electrically contacting portion 89 of the terminal 86 is tightened with the nut 111 the an arrow Z1 direction, big torque on the terminal 86 causes securing force of the terminal 86 to be weakened, whereby the terminal 86 slips off, gets rickety, and damages the plate body 88. Further, this gives bad influence on the electronic parts 107 (FIG. 14) connected to the middle portion of the terminal 86. If the small hole 106 (FIG. 14) is modified to a larger one to avoid the above drawback, cross-sectional area of the terminal 86 decreases, thereby increasing electric resistance of the terminal 86 and reducing mechanical strength thereof.
And, as shown in FIG. 13, though positioning of the busbar 87 can be done at the insert-molding thereof, positioning of the terminal 86 for voltage detection is difficult because the terminal 86 is narrow and long. Also, when the terminal 86 and the busbar 87 are set in the metal mold 102 or when the insert-molded product is taken out of the metal mold 102, there would be a danger that an operator touches the hot metal mold 102 and gets scalded, thereby bringing about bad workability and high manufacturing cost.
Further, in the battery connection plate 85 (FIG. 12), because at least two kinds of parts, namely the busbar 87 and the terminal 86 for voltage detection, are insert-molded at the same time, a lot of man-days is required for a preparation stage of the insert-molding, and simultaneously works are complicated because of many kinds of and a number of number of parts.
If the terminal 86 for voltage detection and the busbar 87 are integrated so as to reduce the number of parts, heat radiation and electric resistance varies according to the shape because the busbar 87 acts to radiate heat from the battery. Because range for electric wires connectable to the terminal 86 for voltage detection depends on material and shape of the terminal 86, it has been difficult to integrate the terminal 86 with the busbar 87. In case that the same material is used, a terminal 114 for voltage detection has to be thinner than a busbar 113 form viewpoint of heat radiation and electric resistance, as shown in FIG. 17, which causes high cost.
Otherwise, in case that the terminal 86 is insert-molded in the plate body 88 after the electric wire 90 (FIG. 12) is pressure-welded to the terminal 86, positioning of the terminal 86 is difficult because a plurality of electric wires 90 get tangled, thereby causing bad workability of the insert-molding.